1. Field of the Invention
The present invention relates to a method for processing a non-metallic substrate, and more particularly, to a method for cutting a non-metallic substrate, which optimizes a shape and an arrangement of an energy source for rapidly heating the non-metallic substrate, thereby increasing a cutting speed and also improving the quality of a cutting plane.
2. Description of the Related Art
Generally, a non-metallic substrate may be formed of silicon or glass.
For example, a non-metallic substrate silicon substrate may be used as a mother material of a semiconductor product for storing a massive amount of data per unit area or processing the massive amount of data per unit time.
Further, a non-metallic glass substrate may be used as a mother material of an LCD (liquid crystal display) panel of an LCD device having a much lower size and lighter weight than a CRT (cathode ray tube) type display device.
Recently, in order to maximize productivity of a product, a plurality of products, for example, the semiconductor chips or the LCD panels, are simultaneously formed on the non-metallic substrate as described above and then separated from each other.
For example, where the non-metallic substrate is the silicon substrate, a plurality of semiconductor chips is formed thereon, and then respectively separated and packaged, thus a plurality of semiconductor products can be produced from one silicon substrate.
Where the non-metallic substrate is the glass substrate, a plurality of display panels is formed thereon using a common fabricating process, and then separated so as to fabricate individual LCD panels, thereby maximizing the productivity of the product.
Because a plurality of LCD panels is simultaneously formed on the non-metallic substrate, the plurality of LCD panels goes through a separating process. Since the separating process is almost performed at the last stage of the LCD manufacturing process, if a defect is generated in the LCD panels during the separating process, the productivity is drastically reduced.
Further, since it is nearly impossible to cure the defect generated during the separating process, the defect in the separating process greatly lowers the productivity.
In order to separate each of the LCD panels from the non-metallic substrate, there has been used a contact-impact type cutting method.
In the contact-impact type cutting method, a scribe line is physically formed on a surface of the non-metallic substrate in a groove shape. Then, an impact is exerted on the scribe line so as to separate each of the products from the non-metallic substrate.
A diamond cutter is used as a conventional separating apparatus. The diamond cutter is provided with a diamond blade in which cutting diamonds are finely inlaid into outer circumferential surface portions of a thin circular plate and a rotating device is disposed at a center portion of the circular plate, and an impacting device for exerting a slight impact on the non-metallic substrate.
However, there are so many problems in the contact-impact type cutting method, therefore, the conventional cutting method causes the productivity to be greatly reduced.
Particularly, where the non-metallic substrate glass substrate is separated using the contact-impact type cutting method, an unexpected portion of the glass substrate is frequently cut.
This problem is caused, for example, by a cutting plane of the scribe line being roughly formed during formation of the scribe line on the non-metallic substrate.
If the cutting plane of the scribe line is roughly formed, as described above, a stress concentration phenomenon occurs at the rough cutting plane. Thus, a fine crack may be easily generated by a small stress applied from an outside. In addition, the fine crack rapidly spreads by a further applied small stress, vibration or impact. Finally, an undesired portion of the glass substrate is separated.
If the unexpected crack is spread to the display panel formed on the glass substrate, as described above, the unrepairable and serious defect is generated in the display panel.
Further, when the non-metallic substrate is separated using the conventional contact-impact type cutting method, since the non-metallic substrate is directly processed, chippings are generated in large quantities, so that a cleaning process for the separated non-metallic substrates is needed. Therefore, the number of process is increased and, correspondingly, productivity is decreased.
Alternatively, in order to cut the non-metallic substrate using the diamond blade, a cutting area including a margin corresponding to at least a width of the diamond blade has to be secured on the non-metallic substrate. However, it is difficult to maximize an effective surface area of the non-metallic substrate, on which the products are formed due to the cutting surface area.
The present invention provides a method for cutting a non-metallic substrate, in which the non-metallic substrate is separated without a cleaning process using a cutting tool and a non-contact type method so as to prevent a cutting failure of the non-metallic substrate, thereby maximizing an effective surface area on which products are formed in the non-metallic substrate and also increasing a cutting speed.
In one aspect, there is provided a method for cutting a non-metallic substrate. In this method, a first laser beam having a first axis and a second axis is scanned onto a predetermined cutting line formed on the non-metallic substrate to heat the cutting line. A length of the first and a length of the second axis have a ratio of about 40:1-80:1. A thermal stress is applied to the non-metallic substrate to form a scribe line. A second laser beam is scanned along the scribe line to cut the non-metallic substrate. The thermal stress is applied to the heated cutting line by supplying a cooling fluid. The first laser beam may have an elliptical shape.
In another aspect, there is provided a method for cutting a non-metallic substrate. In this method, a first laser beam is scanned onto a predetermined cutting line formed on the non-metallic substrate to heat the cutting line. A thermal stress is applied to the non-metallic substrate to form a scribe line. A second laser beam is scanned along the scribe line to cut the non-metallic substrate. The second laser beam has a first axis and a second axis, lengths thereof having a ratio of about 1.1:1-10:1. The thermal stress is applied to the heated cutting line by supplying a cooling fluid.
In still another aspect, there is provided a method for cutting a non-metallic substrate. In this method, a first laser beam is scanned onto a designated cutting line formed on the non-metallic substrate to heat the cutting line. A thermal stress is applied to the non-metallic substrate to form a scribe line. A second laser beam is scanned from a portion spaced apart from an end portion of the first laser beam by a distancexe2x80x94less than or equal to 30 mm, to cut the non-metallic substrate. The thermal stress is applied to the heated cutting line by supplying a cooling fluid.
In yet another aspect, there is provided a method for cutting a non-metallic substrate. In this method, a first laser beam is scanned onto a predetermined cutting line formed on the non-metallic substrate to heat the cutting line. The first laser beam has a first axis and a second axis, lengths thereof having a ratio of about 40:1-80:1. A thermal stress is applied to the non-metallic substrate to form a scribe line. A second laser beam is scanned on a portion spaced apart from an end portion of the first laser beam by a distancexe2x80x94less than or equal to 30 mm, to cut the non-metallic substrate. The second laser beam has a third axis and a fourth axis, lengths thereof having a ratio of about 1.1:1-10:1. The thermal stress is applied to the heated cutting line by supplying a cooling fluid.
According to the present invention, the non-metallic substrate is cut in a non-contact and non-impact manner, thus the quality of a cut face is enhanced, the cutting is made as desired, and the cutting speed is maximized.